The virtual network refers to a computer network constructed by some network apparatuses (such as an exchanger, a router) by the ISP (Internet Service Provider) with the virtualization technology. The generation of the virtual network provides significant advantages for both the ISP and the user. For one hand, the ISP may provide a plurality of virtual networks, based on the current physical network architecture, to meet diverse demands of various uses, thus improving the utilization ratio of network apparatuses and reducing the network running and maintenance cost. For the other hand, the user may hire virtual networks with different capacities according to specific business demands so as to greatly reduce the cost of purchasing and deploying of apparatus, and in the mean time, the virtual network may be regarded as a private network in logic so as to meet the specific business demand by deploying the private network protocol.
The virtual network consists of the virtual nodes and the virtual links. The process of mapping the virtual nodes and the virtual links to the physical nodes and the physical links respectively is called as virtual network mapping. As everyone known, the Internet is actually an interconnection of different network domains which belong to different ISPs. Each ISP will not let other ISPs know core information of its physical network architecture, which results in the limitation of the virtual network mapping within a single domain. However, the coverage area of a single domain is very limited, while the business of the user may relate to a plurality of different domains. Therefore, the conventional intra-domain virtual network cannot fully meet the business demands of the user, which hinders a large scale application and promotion of the virtual network.